Fixes std.meta.Tuple and std.meta.ArgsTuple for zero-sized types

[ikskuh]

Using std.meta.Tuple(&[_]type { void }) failed, as void has no alignment. This sets the correct 0 alignment of 0-sized types

[FireFox317]

One thing to consider here is that we might want to change the implementation of @alignOf to return 0 for 0-sized types. Then there is no need to special case the 0-sized types (which is I think the philosophy of Zig?).

[daurnimator]

One thing to consider here is that we might want to change the implementation of @alignOf to return 0 for 0-sized types

See #4016

[ikskuh]

I think we should merge the PR and fix it later when #4016 is decided. My project is now broken for two weeks 🙈